M20 B3x Naturally Aspirated Stroker build past, present and future

[Mr Mpower]

when i had my first exhaust done the BTB2 6-2 headers were 1-5/8" into 1-7/8" collectors and the shop just made the rear 2.25" from where the BTB collectors ended. 2.25" is more common for cats, resonators, mufflers etc so that's really the only reason it is 2.25" this was not by engineering or calculations but i didnt want to change the entire setup so left it.

really nice advise then!, thanks again!

[nando]

Huh, I missed that whole post about your exhaust. Mine almost exactly matches your diagram for the 4th harmonic. I'll almost certainly move that further down next time I redo it, although I have a single exhaust and fitting the cat and 2 mufflers won't be easy that far down the line (maybe I'll just ditch the cat).

[bmwmaster81]

Just because a a Lot of discussion hapened already regarding exhaaust an so on. I switched from stock 325i exhaust to custom built, with headers.....xpipe....Sport Cat.....with 2x 2inch Pipes Front to end.

It now Runs 16 sec 100 to 200 km/h and that ist 1.5 sec faster than before.

https://youtu.be/GCX0iUCoNF4

I think It must be an 15hp gain.

And I think a Stock m20b25 surely needs 25sec.

[digger]

sounds about right for a stock 325i

[hasa]

Been working on a side project for an ATI vibration damper for the M20 that's essentially plug and play, it is fairly well developed from a design point.

Any news about this?

[digger]

Any news about this?

they have been backlogged so focussing on filling orders and supply of non custom / regular off the shelf stuff due supply chain /covid issues etc to so not anytime soon. i will be contacting them again to see if they have capacity to do progress this.

[hasa]

OK I understand. M20 is legacy engine nowadays so there is not much demand for this kind of products.

Something like this could perhaps be utilised for M20 ? https://www.summitracing.com/parts/ati-918040

[digger]

Something like this could perhaps be utilised for M20 ? https://www.summitracing.com/parts/ati-918040

Probably, if you are ok modifying timing covers and pulley setups you could get an existing product to work I did see something from user whodo iirc . If you went to electric water pump it would simplify things

[ForcedFirebird]

I have yet to get pics from my client that is using one. He modified an ATI to fit the m20 crank snout and put a vee belt pulley on it. He blew apart the stock damper at 8500rpm - took out the water pump, radiator, and even the CPS bracket was shattered. You can purchase 60-2 laser/water cut reluctor rings for short money.

[hasa]

I've also tried to figure out if E21 lower timing gear and M50 harmonic balancer could somehow work together in M20. Running electric water pump could perhaps simplify things in that concept.

[moatilliatta]

It seems like a handful of those 60-2s come flying apart.

[mikey.antonakakis]

Thanks for this thread, really got the gears turning for me on my VGT build. Pretty dead set on 84mm stroker. Love that you’re using EngMod4T, I’ve spent a lot of time in the 2-stroke version.

[digger]

Thanks, I have a big interior project coming up

• new dash
• new centre consoles
• new under dash panel
• new heater core and valve
• new evap and lines
• new compressor
• replacement carpet
• fix speakers and add genuine tweeters
• new plastic sill plates
• new gauge cluster for centre console
• massive booster delete with dual m/c (if I don’t like will do a slightly smaller booster ) to allow new airbox
• various bits and pieces

which should pave the way to start back on engine build

[digger]

Latest looks, subtle changes

[digger]

DId a booster and m/c swap along with 300mm/de BBK.


-Year and model of your E30: 89 325is RHD vehicle

-Intake manifold used in swap: m20 RHD ITB setup with own custom airbox. PLanning a new airbox and trumpets hence the mod as it creates more space

-Brake booster donor car: e93 320d

-Brake booster part number:34336779733

-Brake booster manufacturer and manufacturer PN or identifying marks: i thought TRW make them but cant be sure? it has single vacuum port, i oriented port closest to engine but it was on the otherside on the doner vehicle. some have 2 vacuumm ports just block one off.

-Parts needed:
e93 booster 34336779733
e90/92/93 m/c RHS version with ports on outside 25/22 34336785664
e93 clevis pin 34336753646
spring clip 07129904567
new o-ring for M/C 34311160617
new bung for M/C reservoir 2 x 34311160133
rubber hose for remote mount reservoir
remote reservoir 2002 bottle FTE brand p/n 9790000
connector for M/C to fit hoses for remote reservoir 2 x 34321102282
Booster vacuum port bung 34336765316
2 x M10x1 bubble tube nuts
2 x M12x1 bubble tube nuts
3/16" cunifer brake line
flare tool https://www.amazon.co.uk/Laser-TOOLS...01N39OIKA?th=1
line cutter

-Modifications needed:
booster unmodfied as clevis bolts right up with RHD vehicles as the clevis position is within a couple mm or the stock one but you adjust the brake light switch as required as pedal height changes a bit
to fit booster trim away the firewall insulation with a box cutter and/or scissors
trim the plastic firewall clips that retain the hard lines near the booster and lightly massage the lines by hand so boosters sits flush on firewall
i made two (2) new lines from ABS unit to the M/C using cunifer 3/16" tube and M10x1 tube nuts at one end (ABS) and M12x1 at the other end (M/C).
i dissassembled the rear pressure limiting device and removed the guts and reassmbled (optional step)

-Comments on pedal feel and stopping power: Brake are best they ever felt. i did this with 300mm.de 4x100 312x28 FR and 294x19 RR setup fully rebuilt with new pistons the e34 540i front calipers (60mm piston) and e36 m3 rear calipers (40mm piston)

after replacing almost entire brake system sans hardlines and ABS unit bleeding took a few goes and suggest using a Motive pressure bleeder with BMW adapter and following the steps in link a couple times or you wont get the system bled and pedal will be long and soft

https://bmwe30cabriolet-wdm.blogspot.com/2019/08/how-to-purge-your-abs.html

you could try a e92 m3 or e60 m5 M/C if you want a harder pedal but the 25/22 seems pretty close to perfect for my preferences.